Austrian Early Career Conference 2024

Contribution:
Talk

Authors:
Alexander Ebenbichler

Affiliations:
University of Innsbruck

Title:
Alignment of diffuse interstellar bands

Abstract:
Context. There have been many attempts to identify families of diffuse interstellar bands (DIBs) with perfectly correlating band strengths. However, although major efforts have been made to classify broadly based DIB families and important insights have been gained so far, no family has been identified with sufficient accuracy or statistical significance to prove that a series of selected DIBs originates from the same carrier. This can be attributed in part to the exclusive use of equivalent widths to establish DIB families.
Aims. In a change of strategy we search for DIBs highly correlated in both band strength and profile shape. This approach increases the chance that correlating DIBs are members of one family, and originate from the same carrier molecule. Subsequently, we search for correlations between DIB profile families and atomic interstellar lines, with the goal to further constrain possible DIB carriers.
Methods. We adapt the well known method of time-series alignment to perform spectral alignment, that is, DIB alignment. In a second step, we analyse the alignment results using clustering analysis. This method requires a statistically significant data set of DIB sight lines. The ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES) data are perfectly suited for this application.
Results. We report eight DIB families with correlating strengths and profiles, as well as four previously unreported DIBs in the visual range using DIB alignment. All profile family members show Pearson correlation coefficients in band strength higher than 0.9.